Masters,
I am trying to learn the serial mouse driver for linux kernel. On the kernel source tree I find out these macros and I am unable to find out the meaning of these macros. Please anyone help me to understand these.
These macros are defined in linux/serio.h and are used in the sermouse.c (driver code for serial mouse in linux).

#define SERIO_PROTO 0xFFUL
#define SERIO_MSC 0x01
#define SERIO_SUN 0x02
#define SERIO_MS 0x03
#define SERIO_MP 0x04
#define SERIO_MZ 0x05
#define SERIO_MZP 0x06
#define SERIO_MZPP 0x07

I used Mr google but yielded no result. I think these macros indicate some certain protocols but I dont know what protocols. Can anyone help me to understand these.

To me they identify different serial mouse models, so that the driver can be compiled with the proper instructions, especially to manage the behaviour of the 3rd button (if any). The differences about various models are well illustrated on the Wikipedia's Mouse page.